Extinguish the candle, apprentice, so that we may See.
I made sure to apply that rule when one of my players took the Dungeon Delver feat to get advantage on checks to spot traps and secret doors. (We're playing Dungeon of the Mad Mage, so there are a lot of both.)
Darkvision is a fictional magical ability with its function clearly defined by the game rules. Infravision is a vaguely-defined mechanic based on a real scientific phenomenon that people commonly misunderstand, and then make poor game rulings based on those real-world misunderstandings. Also, again with it being more of a pain to adjudicate.
Not clearly enough to avoid confusion among fans. Clearly. Since there’s constant references to people not understanding or not applying the rules for darkvision.
I’ve seen far more misunderstanding around 5E’s darkvision than infravision. 5E’s been out, what 10 years while AD&D’s been out, what 45-47 years. Still more confusion over darkvision.
I'm confused already. Does it only let you see creatures and torches? Can you use it to navigate in an environment that lacks major temperature gradients? Are undead and constructs invisible to infravision? Does moonlight count as a light source shedding light on the creature possessing infravision? Does it provide enough detail to let you recognise an individual?
No. You see heat. Anything that's a significantly different temperature than the ambient heat level would stand out.
Nope. If everything's the same temperature, it would all blend together. What you see in most infrared or thermal images is a combination of image enhancement and thermal imaging. Without that image enhancement, everything that's the same temperature would blend together.
Only if their temperature doesn't vary significantly from the ambient temperature. The more they move, the more they'd heat up (if real-world physics applies), so things like feet that scrape against the floor, joints that move, etc would stand out.
The moon reflects light and heat. It doesn't mess with infrared goggles, but no idea if it would mess with someone with infravision. This might be where Gary messed up.
If you had identical twins in the same clothes you couldn't tell them apart, but you'd still see things like the shape of clothes, outlines, height difference, body shape, body type, etc.
Even in that case, they still have a weird thing where if there's a dim light source around them they can see better at long range than short range. Or a torch would give three bands: see fine 20', see poorly 20' more, then see fine for another 80'.
Ok...
No. You can see everything within the range. All objects and creatures vary in temperature from the things around them, even if only minimally.
Yes. As long as there are any temperature gradiants, you notice it. If there is no difference in temperature, then effectively everything would be the same color and blend together, effectively making your infravision ineffective.
No, you can see them unless they are precisely the same temperature as the ambient temperature around them. VERY rarely would anything like this happen unless artificially created.
Sadly, yes, since the range of moonlight is effectively infinite. Infravision really only helps in areas of complete darkness.
As much detail as you could derive depending on how close you are to the person, sure.
Because elves do a lot of their celebrations during the night, especially under moonlight, etc.?
